Genesis 35:29
And Isaac gave up the ghost, and died, and was gathered unto his people, being old and full of days: and his sons Esau and Jacob buried him. And Isaac gave up the ghost, and died, and was gathered unto his people, being old and full of days: and his sons Esau and Jacob buried him.
Genesis 35:29 records Isaac's death briefly as an old-age death after a full lifespan, described as old and full of days, without naming any disease. He died when his sons Jacob and Esau were 120 years old. He lived many years beyond the blessing he gave to Jacob.
What he later observed in Esau and Jacob convinced him that the blessing rightly belonged to Jacob. His long life helped preserve the knowledge God had taught Adam and pass it through successive generations to Jacob, the father of the tribes of Israel. His death exemplifies the healthy deaths recorded in early biblical history, in contrast to later deaths caused by disease.